The invention relates generally to power-driven conveyors and, more particularly, to hinge rod retention structure in plastic conveyor belts constructed of rows of modules pivotally interconnected by hinge rods.
Conventional modular plastic conveyor belts and chains are constructed of modular plastic links, or belt modules, arranged end to end and side to side in rows. Spaced-apart hinge eyes extending from each end of the modules include aligned rod holes. The hinge eyes along the leading end of a row of modules are interleaved with the hinge eyes along the trailing end of an adjacent row. Hinge rods, journalled in the aligned rod holes of interleaved hinge eyes, connect adjacent rows together end to end to form a conveyor belt of selected length and width capable of articulating about a drive sprocket or drum at the hinges formed between adjacent belt rows.
But belt motion and belt tension can cause the hinge rods to migrate along the hinge or to lengthen. If a rod is allowed to extend out of the hinge beyond the side of the belt, the rod can catch on conveyor structure or other objects and cause damage. Consequently, it is important that hinge rods be contained within the belt. Many conventional modular plastic conveyor belts use a sliding retention member that can be manually moved from a closed position occluding the rod holes to an open position in which the aligned rod holes are accessible for rod insertion or removal. To prevent the retention members from accidentally moving from the closed position to the open position while the belt is running, the retention member is designed to require a significant force to move it out of its closed position. Before a hinge rod can be inserted into the aligned rod holes, a retention member must be moved out of the way. Once the rod is fully inserted, the retention member may be returned to its original position. Sliding the retention member out of the way to allow access to the hinge, pushing the rod into the aligned rod holes, and sliding the retention member back into position occluding the rod holes and retaining the hinge rod is one of the most time-consuming and physically challenging steps in the assembly and repair of modular plastic conveyor belts. And, if the retention member is inadvertently left in its open position, the unconfined rod can work its way out the side of the belt while the belt is running.
Consequently, there is a need for a rod retention system for a modular plastic conveyor belt that is self-closing and does not require the time and physical effort of conventional systems.
This need and other needs are satisfied by a modular plastic conveyor belt edge module embodying features of the invention. The edge module comprises a module body, a retention member, and biasing means. The module body extends longitudinally from a first end to a second end, laterally from an inside edge to an outside edge, and in thickness from a top side to a bottom side. The module body includes a first set of hinge eyes spaced apart along the first end and a second set spaced apart along the second end. The hinge eyes form rod holes that are laterally aligned to define a first rod passageway at the first end and a second rod passageway at the second end. Outside edge structure in the module body defines a chamber near the outside edge of the module body. The chamber intersects the first rod passageway and extends in a slide direction to a far end. The retention member, which is received in the chamber, defines a slide axis and includes a guide surface and a rod-contacting face oblique to the slide axis. The retention member resides in the chamber with the slide axis of the retention member extending in the slide direction. The rod-contacting face obliquely faces the outside edge of the module body. The outside edge structure also includes a guide formed along the chamber that engages the guide surface of the retention member. The guide guides the retention member in the slide direction along the chamber. The retention member slides between a first position and a second position. In the first position, the retention member occludes at least part of the first rod passageway. In the second position, the first rod passageway is unoccluded. The biasing means, such as a spring, resides in the chamber and urges the retention member toward the first position. When the hinge rod is inserted laterally from the outside edge of a belt, the end of the rod slidingly bears against the rod-contacting face of the retention member, which forces the retention member to slide in the slide direction along the chamber against the biasing means to the second position until the retention member clears the first rod passageway. The end of the rod then slides off the rod-contacting face into the unoccluded first rod passageway.
In another aspect of the invention, an edge module for a modular plastic conveyor belt comprises a module body with outside edge structure forming a chamber that slidably receives a spring-loaded rod retention member. The module body extends longitudinally from a first end to a second end, laterally from an inside edge to an outside edge, and in thickness from a top side to bottom side. The module body includes first and second sets of hinge eyes spaced apart along the first and second ends of the module body. Rod holes formed in the hinge eyes and aligned laterally along the first and second ends form first and second rod passageways along the first and second ends. Outside edge structure in the module body forms a chamber near the outside edge of the module body. The chamber intersects the first rod passageway and extends to a closed far end. A spring extends between the far end of the chamber and the retention member to urge the retention member toward the first end of the module body into a position at least partly occluding the first rod passageway.
In yet another aspect of the invention, an edge module for a modular plastic conveyor belt comprises a module body that extends longitudinally from a first end to a second end, laterally from an inside edge to an outside edge, and in thickness from a top side to a bottom side. The module body includes first and second sets of hinge eyes spaced apart along the first and second ends of the module body. Rod holes formed in the hinge eyes are aligned laterally across the first and second ends of the module body. The aligned rod holes define first and second rod passageways along the first and second ends. Outside edge structure defines a chamber near the outside edge of the module body. The chamber intersects the first rod passageway and extends in a slide direction to a far end. A retention member slidably received in the chamber includes a rod-contacting face at the end of the retention member nearer the first end of the module body. The rod-contacting face is oblique to the first rod passageway and to the slide direction.
In still another aspect of the invention, an edge module for a modular plastic conveyor belt comprises a module body extending longitudinally from a first end to a second end, laterally from an inside edge to an outside edge, and in thickness from a top side to a bottom side. The module body includes a first set of hinge eyes spaced apart along the first end and a second set of hinge eyes spaced apart along the second end. The first set of hinge eyes forms rod holes aligned laterally to define a first rod passageway; the second set of hinge eyes forms rod holes aligned laterally to define a second rod passageway. Outside edge structure in the module body forms a chamber near the outside edge of the module body intersecting the first rod passageway and extending to a far end. A retention member received in the chamber slides between a closed position at least partly occluding the first rod passageway and an open position clear of the first rod passageway. Biasing means urges the retention member toward the closed position occluding the first rod passageway.